High precision bellows for a wide range of applications

To meet the most exact specifications of our customers, we produce a wide range of hydroformed metal bellows.

They are key components in a large number of applications and thus manufactured with utmost care and reliability.

Established in 1956, as a metal bellows manufacturer that places extremely high values on precision, we only use state of the art technologies, tools and machines in our new production site in Poland which started its operation in 2007. We monitor every stage of the manufacturing process, starting with the deep-drawing of metal tubes up to hydroforming and leak testing. In this way we ensure that irregularities would be noticed immediately during the production and are able to guarantee long life expectancies for all our metal bellows. Plenty of test devices help to analyze the consistency.

Designing and manufacturing of Mera Bellows metal bellows

Designing metal bellows is a challenge. Usually a thin wall-thickness is needed in order to meet flexibility requirements. Therefore, metal bellows often have a lower wall-thickness than all other parts of the system in which they are implemented. Different types of corrosion may occur in sometimes extreme environments. As an established metal bellows manufacturer, our experience and large choice of materials, help to find suitable and sustainable solutions balancing all demands. After the specification of surrounding media (gas or liquid) to which the internal and external bellows surfaces will be exposed, also vibration characteristics and the maximum amount of stroke must be determined. This states the axial compression or extension that the metal bellows have to perform. The geometric parameters also have to be selected: length, inside and outside diameter of convolutions, wall-thickness (one or two-ply design) and specifications of the bellows endings.

Our metal bellows production starts with a metal-strip that is cut into blanks using a hydraulic press. After cleaning and decreasing the cups, they are deep-drawn into thin-walled tubes with closed ends in several steps. The hydroforming process works with water pressure which is defined depending on the outside diameter and wall-thickness. Simultaneously, a customized cassette is being moved in the axial direction of the metal tubes, which leads to an even formation of convolutions that gives the metal bellows their well-known shape. Afterwards, the seamless hydroformed metal bellows are cut to the desired length, cleaned using eco-friendly paraffin and stress-relieved. Mera Bellows has the possibility of applying a final compression operation in the direction of the axis – it creates an omega profile that (at a specified length) allows more convolutions than a sinus-shaped profile. This enables the metallic bellows to compensate larger movements and also improves efficiency of axial movement absorption by equalizing expansion stress. Special coatings are available on demand. Our large-scale production is based on Lean-Management.

Advantages of our metal bellows

It is important to emphasize the advantages of these seamless metal bellows constructions. Compared to welded bellows, they show a lower variance in diameter and wall-thickness and thus have a significantly more stable performance with regard to their pressure characteristics and spring rate. Lifecycle tests also show statistically remarkable results for our seamless precision bellows since a weld is usually seen as the weakest point.

We are a long established producer of open-ended hydroformed bellows which can be used for example, as metallic hermetic seals while absorbing axial, angular and lateral movements. Due to the deep-drawing technologies, we are additionally able to supply high- precision metal bellows with one closed end. This allows many more design possibilities. The metal bellows with bottom are widely used in measuring and controlling applications. They can convert pressure into movement. The main focus here is the spring rate (N/mm) that Mera Bellows can precisely guarantee as a standardized large-scale metal bellows manufacturer with special spring-rate testing devices.

Metal bellows applications

In pumps, bellows made of nickel-based alloys and stainless steels are widely used – for higher corrosion, pressure, and temperature requirements. Metal bellows are also convincing as maintenance-free hermetic sealing element in valve technology, as they protect the valve stem (spindle) from surrounding media. Furthermore, bellows- and metal bellows assemblies with different possible flanges are used in pressure, temperature and altitude sensors. Other examples of usage are volume compensators for aerospace, metal bellows couplings for automotive or medium-voltage vacuum switch gears (circuit breakers) for energy distribution. Of course, hydroformed bellows can also simply be used as elastic connectors, for instance in solar thermal systems. As long lasting expansion joints our stainless steel bellows compensate vibration, tension, and thermal expansion between solar collectors. Customized end solutions allow an easy and time-saving installation with O-rings and convenient plug-in system.